Journal of Neuroscience, Vol 6, 1970-1975, Copyright © 1986 by Society for Neuroscience
Catecholamine, serotonin, and substance P-like peptide containing intrinsic neurons in the mudpuppy parasympathetic cardiac ganglion
DS Neel and RL Parsons
The mudpuppy cardiac ganglion contains 2 neuron types: large
parasympathetic postganglionic projection neurons and smaller intrinsic
neurons originally described by McMahan and Purves (1976) as intensely
fluorescent (SIF) cells. The function of these SIF cells, present in the
mudpuppy cardiac ganglion, is unknown. Further, direct application of
catecholamines, which are thought to be contained in SIF cells, to the
parasympathetic postganglionic cells has no effect (Hartzell et al., 1977).
As SIF cells in other ganglion preparations recently have been shown to
contain putative transmitter substances in addition to catecholamines,
immunocytochemical experiments were conducted to test for the presence of
additional transmitter substances in the SIF cells within the cardiac
ganglion. Whole-mount septal preparations were dissected from Necturus
maculosus and processed for indirect immunocytochemistry. The results
indicated that many of these intrinsic neurons contained 5-HT or a
substance P-like peptide, or both. Many small intrinsic neurons which
contain either substance P or 5-HT were also positive for
aqueous-aldehyde-induced fluorescence, indicating the presence of a
catecholamine. Finally, some of these cells appeared to contain all 3: a
catecholamine, 5-HT, and a substance P-like peptide.